IMO you NEVER EVER can have too many RAMBUS boards!
Come to think of it, I have 2 x 840 OR Slot 1, ECS P4ITA S423, Abit-TH7II S478, an Intel Desktop Board I850 S478 and a dead Gigabyte GA-8TM S423. In total just 5 fully working RAMBUS boards and this is after 6 years of "collecting"! The RAMBUS boards and Slot A boards are on top of my list anytime any day.
Of course that I also like Slot 1, Sk.3 and Sk.4 beasts ... and many many more ... too many to count ... too big to fit in memory. I grew up reading so much about them that when I find on of them I say: Hellow Old Friend, stay a while and rest! You are safe now! No recycler is going to get his grubby hands on you.
I guess I don't know when to stop anymore.
I need to make a headcount and see what I have in my collection. The last time I did this was a few years ago.
I guess that I have around 60 motherboards and a couple of hundred CPUs plus at least 100 graphic cards, 50+ CPU coolers, 20-30 fully restored ODDs, cables and you name it!
Also I need to find a i820 slot 1 motherboard.
Sheeshhh begone demons of retro HW "hoarding" ( I still considet myself light weight)